Motion-converting mechanism



Aug. 4, 1925.

c. B. FORBERG MOTION CONVERTING MECHANISM Filed May 27, 1922 .....,....HHHHHWHHH.mmu'zy Patented Aug. 4, 1925.

UNITED STATES PATENT OFFICE.

CHARLES B. FORBERG, OF CHICAGO, ILLINOIS, A'SSIGNOR, BY MESNE ASSIGNMENTS,

TO HELIOS MACHINE COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF DELA- WARE.

MOTION-CONVERTING MEGHANISM.

Application filed. May 27, 1922. Serial No. 564,113.

To all whom it may concern:

Be it known that I, CHARLES B. Fonnnnc,

a citizen of the United States, residing in Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Motion-Converting Mechanism, of which the following is a specification.

My invention relates to mechanism for accomplishing a mechanical movement and is particularly adapted for use to convert a continuous rotary movement into an in termittent rotary movement, such as is required for the operation of a film-feeding drum in motion picture projecting apparatus.

The principal object of the invention is the provision of an improvement in motion converting mechanism adapted for employment in moving picture apparatus which greatly increases the speed with which the film may be moved, without detracting from clearness, or effectiveness in projection of the picture.

Another important object of the invention is the provision of motion converting mechanism so constructed and arranged as to eliminate, in large'measure, the wear upon the operative parts while, at the same time, minimizing the noise incident to operation and providing a positive and exact control and action of the driven part.

A further object of the invention is the provision in a construction of this character of a cam part which is of peculiarly effective form and which is constructed of hardened material particularly adapted to resist wear and which may be set in a cam disk of which it forms a partwithout requiring the use of such material for the entire disk.

, Another object of the invention is the provision of a construction of this character in which the intermittently rotated part is positively held against rotation by mere surface contact between the cam disk, orother actuatingpart, and the operating member secured to the driven part, thus eliminating the requirement forparticular holding means to prevent rotation of the intermittently driven shaft during the period of rest thereof, which, in the present instance, is vat the time the translucent film is undergoing exposure for the projection of a picture. I

which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings,

Figure 1 is a plan view of a device in which my invention is embodied, the same being shown in a suitable support, or housing;

Fig. 2 is a sectional view through the housing, showing the cam disk in end elevation;

Fig. 3 is a perspective view of the operat ing parts, the housing being fragmentarily shown; and 1 Fig.4 is a detail perspective of the operating cam and driven part, showing the operative relationship thereof.

Forpurposes of illustration, I have shown uponthe drawing an embodiment of my invention in form adapted to accomplish the intermittent, or step movement required in the feeding of a film past the light aperture in a motion picture projecting apparatus.

A casing, or housing 11, of any suitable character but preferably of such weight as to provide a .firm supporting frame, has journaled therein a shaft 12, which is adapted to be continuously rotated from the source of power provided for operation of the apparatus, which, in the usual instance, is a small motor. It will be understood that suitable gearing is interposed between the motor and this shaft to obtain the desired speed and relative action. Suitable bearings 13 and 14: are provided in the frame for this shaft and a cam disk 15 is fixedly securedto the shaft in any known or approved manner, the means of attachment in the present instance being a set screw 16 extending through an aperture in a sleeve part 17 projecting from one side of the disk 15. The peripheral surface of said disk 15 is flattened, as indicated at 18, and preferably is cut away on each side at 19, leavingthe part 18 of suflicient width to 'faces provide a track for a purpose to be hereinafter described and providing means for directing lubricating oil, which is scraped from the track 18, about the disk and onto -the cam part to be later referred to, from which it is again directed onto the track part 18.

In the peripheral surface of the disk 15, I provide a double cam part, generally indicated by the reference character 21, and which preferably is contained in a hardened steel block 22, which is set in a cut-out part of the disk and secured in place by screws, or pins 23. This renders possible the substitution of new cam parts to replace worn ones, without the replacement of an entire new disk and, furthermore, permits the utilization of hardened and relatively expensive material in the cam, Without requiring that the entire disk be constructed of such material.

A film-feeding drum, or spool 24, is mounted on a shaft 25, which extends through the housing 11 and is rotatably held by a sleeve, or hearing member 26, which in the present instance extends in wardly a distance from the wall of the housing. To provide the desired effect in projection ofpictures from the film, it is necessary" that' the spool '24 be operated only intermittently and held firmly in position of rest while the picture is thrown upon the screen, it being desirable in this connection that as high a ratio as possible between the rest period and the period of movement be obtained. In order to hold the shaft 25 positively and firmly against rotation while the picture is being projected, I provide an operating member 30, which, in the present instance, is in the form of a nut having a collar part 27 forming a socket for the end of the shaft 25 and rigidly secured thereto.

During the major part of therotation of the disk 15 aside of the nut 30 is in firm contact with the surface 18 and the shaft 25, which is securely mounted in the housing 11 or otherwise, is held against rotation or vibratory movement. Each revolution of the disk accomplishes a quarter turn of the shaft 25 through the action of the cam 21 upon the nut 30. The cam 21 consists of opposed helical surfaces 28 and 29, which are so arranged that the side of the nut 30 which has been in contact with V the track 18, follows the surface 28 and the side which is disposed at right angles thereto is engaged by the surface 29, said surtog'ether accomplishing" a -quarter turn of the part 30 and without appreciable interruption of the surface contact between said part andthe disk. When this cam member is properly generated, the surfacev contact is practically continuous and is-evenly distributed, so as to reduce to a minimum the wear upon the cam surfaces, as well as upon the" member 80.

Furthermore, with this type of construction, the noise incident to the intermittent rotation of the driven part isreduced to a struction with a higher ratio between the period of rest and the period of movement of the driven part, this resulting from the short length of the cam required and the quick turning movement of the member 30. To further eliminate friction between" the disk and the member 30, I prefer to construct the latter with slightly beveled edges, as im dicated at 31, and itwill, of course, be evident that the parts are subject to such change or variation in machine construction as may result in the most efficient action under particular requirements.

Vfith the foregoing constructionandarrangement of the parts, the apparatus ordinarily employed for the general purpose of converting a continuous rotary movement into an intermittent or step movement is greatly simplified and improved through the elimination of special means ordinarily required to hold the driven part against accidental movement during the desired period of rest and complicated operating parts for accomplishing the turning movement. Furthermore, the mechanism provided by my invention is extremely efiicient in action and obtains greatly improved results from the standpoint of clear projection of motion pictures when employed for the purpose of the herein described embodiment of the invention.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention,

or sacrificing all of its material advantages, the form hereinbefore described being merely preferred embodiment thereof.

I claim:

1. Motion converting mechanism, comprising a continuously rotated shaft, a cam disk secured thereon and having a raised flat peripheral surface of less widththan the thickness of said sdisk, said peripheral surface extending throughout the greater part of the circumference of said disk, a separable spiral cam member adapted tobe set in said cam disk to form a continuation of said peripheral surface, a driven shaft terminating in a free end adjacent the peripheral surface of said disk, a rectangular head secured to the free end of said driven shaft, said head being adapted to have one side thereof in free contact With the peripheral surface of said disk tohold the driven shaft against rotation during the major portion of each rotation of the disk and to give said driven shaft a quarter turn by engaging said spiral cam to impart intermittent partial rotation to said driven shaft.

2. Motion converting mechanism, comprising a shaft adapted to be continuously rotated, a cam disk fixedly secured to said shaft and having a fiat peripheral surface of less Width than the thickness of said disk, said surface extending throughout the greater part of the circumference of the disk, an independent double cam member adapted to be fixedly secured to said disk and to form a continuation of said peripheral surface, a driven shaft, a polyhedric nut secured to the free end of said shaft adjacent the peripheral surface of said disk, said polyhedric nut adapted to have one face thereof in engagement with the peripheral surface of said disk to hold said driven shaft against rotation throughout a substantial portion of each rotation of said disk and to impart to said driven shaft a predetermined intermittent rotary movement by engaging said cam, the opposed faces of said cam forming a continuous curve adapted to transfer said nut from one cam face to the other and give substantially a quarter turn to said driven shaft.

3. Motion converting mechanism, comprising a closed housing, a shaft mounted in said housing adapted to be continuously rotated, a cam disk fixedly secured to said shaft and having a raised fiat peripheral surface of less Width than the thickness of said disk, said surface extending throughout the greater part of the circumference of the disk, a separate double cam face membre adapted to be removably secured in a recess in said disk and When so secured adapted to form a continuation of said surface, a driven shaft mounted in one Wall of said housing and terminating in a free end adjacent the peripheral surface of said disk, at polyhedric nut secured to the free end of said shaft, one side face of said nut adapted to ride freely upon the fiat peripheral surface of said disk to hold said driven shaft against rotation and When riding over said double cam member to transmit a predetermined rotary movement to said driven shaft, the side face of said nut being rounded to reduce the friction When in contact With said cam.

CHARLES B. FORBERG. 

